Gaseous pulse amplifier



Sept. 30, 1952 HAGEN 2,612,617

GASEOUS PULSE AMPLIFIER Filed May 12, 1949 INVENTOR.

GZN/V 6. HAGN Patented Sept. 30, 1952 2 2,612,617 GASEOUS rULsE AMPLIFIER Glenn E. Hagen, Lawndale, Calif., assignor to Northrop Aircraft, Inc., Hawthorne, Calif., a

corporation of California.

Application May 12, 1949, Serial No. 92,881

The present invention relates to pulse amplitiers and relates more particularly to, a gaseous pulse amplifier tube and circuit.

In electronic computers, a large number of pulse amplifiers are customarily utilized, these amplifiers incorporating hot cathode electronic,

tubes to provide pulse amplification. As the hot cathodes are heated by passage of an electric current through the tube, the power required for filament use in the computer is high.

, It is an object of the present invention to pro vide a gaseous glow discharge tube capable of pulse amplification. l

It is another object of the present invention to provide a pulse amplifier tube utilizing a glow discharge in place of a filament or heated cathode.

It is a further object. of the invention to provide a pulse amplifier tube having an exceptionally low cathode power requirement.

And it is still another object of the present invention to provide a pulse amplifier circuit uti- 1 Claim. (01. sue- 189) lizing a gaseous glow discharge tube as the am- I plifying element thereof. I

Briefly, the present invention includes a gaseous conduction type of glow tube in which a glow discharge is constantly maintained between the cathode and a glow grid, as by a battery for example. This glow discharge combination acts as an effective cathode. An anode is. provided having a neighboring electrode or control grid held at a potential with respect to the glow grid such that, the cathode glow discharge is just prevented from continuing on to the anode. When a positive pulse is applied to this neighboring electrode, however, the 'glow'discharge can continue on to the anode thusproviding a glow" discharge conducting path from the cathode to the anode. The anode current is supplied through a high resistance, causing a decrease in voltage on the anode, thereby quickly extinguishing the potential needed for urging the glow discharge to continue on to the anode. The change in voltage at the anode is taken as an output in the form of a sharp, high amplitude negative pulse. Thus a small positive voltage pulse at the input results in a large negative pulse at the output.

The invention may be more fully understood by reference to the ensuing description of the appended drawings in which:

Figure l is a longitudinal sectional view of one preferred form of glow tube having the desired pulse amplification characteristics in accordance with the present invention.

Figure 2 is a circuit diagram for operating the tube of Figure 1 as a pulse amplifier.

Referring first to the glow tube shown in Figure 1, an envelope 1 is provided with a cathode stem in the form of a hollow glass cathode tube or pipe 2 having an exterior pinch 3. Inside pipe 2 is, a cylindrical cathode 4 having a cathode lead 5 extending through pinch 3. Around-pipe '2, extending outside of and sealedto the end of envelope l, is positioned and sealed a first grid cylinder or glow grid 6 having interior edges 1 turned over the end of pipe 2 to face the cathode 4. Grid cylinder 6 is held in a mounting clip- 8 to which a first grid lead 9 is attached.

At the opposite, end of the envelope I an anodetube or pipe [0 is passed through the envelope I, coaxial with cathode pipe 2. Anode pipe. [0 ,is longer than cathode pipe 2 and is also provided with exterior pinch ll. A cylindrical anode I2 is positioned in anode pipe [0 having ananodelead l4 passing through pinch ll. Anode l2 however, is not set close to pinch l l but is S aced therefrom to provide room for a mass of gas adsorbing material such as activated carbon grane ules' 15 back of anode l2. Inasmuch as anode pipe I0 is longer than cathode pipe 2, anode l2 can be set so that the spacing of the anode from the interior end of pipe l0 is substantially greater than the spacing of cathode 4 from th interior end of cathode pipe 2.

A second grid cylinder or control grid leis:

positioned and sealed around anode, pipe I10 having inturned edges l8 bending around the inner end of anode pipe I0 to present surfaceto anode [2. Second grid cylinder I6 is also sealed to the end of envelope I and is held in a second mounting clip [3 to which a is connected. I After the tube has been assembled, it is baked out in the usual manner, evacuated, and gas filled. A preferred gas filling is helium gas at mm. pressure of mercury.

The tube is used as a pulse amplifier in aparticular circuit as shown in Figure 2. I

Here the cathode 4 is connected to ground through a resistance 20 bridged bya capacity 21, and a battery 22 with its positive terminal connected to ground. First grid or control grid 6 is connected directly to ground through grid wire 24. nectedto ground through a series input high resistance 25, a shunt resistance 26,; and an input battery 21 whose positive terminal'is connected to ground. An input line 29 is connected to second grid lead .I 1

Second grid or glow grid i6 is con-' In operation, a glow discharge is maintained constantthroughout the operation of the tube, between cathode I and first grid 6.

By mounting the cathode 4 'so that only the inner end thereof enters into the glow discharge and by operating the cathode and first grid at a voltage where the glow discharge covers the entire exposed end of the cathode, the negative resistance characteristics of the cathode glow discharge are, for all practical purposes, completely eliminated, and the device does not tend to oscillate. The metal from which the cathode is constructed may, for example, be of aluminum or similar metal so that sputtering is reduced to a minimum.

' The second grid l6 is maintained at a negative potential to first grid 6, with the anode [2 maintained at a relatively high positive potential.

This prevents electrons from the glow discharge between first grid 6 and cathode 4 from entering the space between anode l2 and second grid l6. Under these conditions, the potential on anode I 2 is not suificient to initiate a glow discharge in the space between anode l2 and second grid 16. However, when a positive pulse is applied to second grid 16 the negative potential thereon is'reduced, and electrons from the oathode glow discharge enter the space between anode f2 and second grid 16 due to the urge of the positive anode I2. When this happens, the gas between anode IZ and second grid I6 is ionized and the entire envelope becomes conducting.

The current from the glow discharge to anode I2,"flowing through output resistance 34 causes a decrease in voltage at anode 'l2 sufficient to quickly quench the glow discharge between anode l2 and cathode 4.1 The change in voltage of the anode is then used as the output, in the form of a sharp, high amplitude negative pulse. In a circuit having battery voltages-of the values outlined above, a 10 volt positive input pulse Pi (Figure 2) at the input, will cause a 300 volt negative output pulse, P0. The voltage amplification factor is therefore 30.

One of the main'advantages of the present invention is that the cathode glow discharge between cathode 4 and first grid 6 requires less current and less power than is normally consumed the hot cathode circuit of most vacuum and gaseous amplifier tubes.

The life of the tube 'canbe materially extended by the use of the activated carbon l5 or other material which adsorbs .gas and releases it to prevent clean-up. In efiect, the use of this adsorbingzmaterial permitsthe use of a very small tube, having an efiective large gas capacity. For example, :the tube used in the circuit described above and using the battery voltage set forth above, is only inches lon and 4 inches in diameter.

From the above description it will be apparent that there is thus provided a device .of the character described possessing'the particular features and the invention is, therefore, claimed in any of its forms or modifications within the legitimate and valid-scope of the appended claim.

What is claimed is:

A pulse amplifier comprising: an envelope con-'- taining an inertgas at cold'cathode glow discharge pressure; "a pair-of coaxial tubes of insulating material passing "through opposite ends of said envelope, said tubes having'their inner ends spaced and their-outer ends sealed; a first cylindrical grid positioned and sealed around one of said tubes; a second cylindrical grid positioned and'sealed around the other of said tubes, said cylindrical grids also being sealed through the ends of said envelope, both of said grids having edges inturned around the open end of the tubes in which they-are positioned; a cold cathode inside the tube. supporting said first grid; an anode inside the tube supporting said second grid, each of said grids and said cathode and anode having leads from said envelope said anode and said cathode havingfacing surfaces normal to the axes of said tubes-and substantially filling the interior cross sections of said tubes, said facing surface also being 'locatedsubstantial distances within said tubes awayfrom the inturned edges of said grids, the facing surface of said cathode being at a greater distance away from the inturned edge of the adjacent grid than the corresponding distance relation of the facing surface of said anode with its adjacent inturned grid edge.

GLENN E. jI-IAGEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Cotton Apr. 26, 1949'v 

